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An extension conflict is one of the most common issues that appear with programs on the Macintosh. However, the range of behaviors that may occur with an extension conflict is varied. Behaviors can be as simple as menu commands appearing as unavailable, or as complex as a crash or freeze with an error message.

Testing for an extension conflict is one of the easiest tests available. To test for an extension conflict, follow these steps:

Quit all programs.

On the Special menu, click Restart and then press SHIFT.

Continue holding SHIFT until a message appears stating that the extensions have been disabled or turned off.

NOTE: This process temporarily turns off add-on components (extensions and control panels) of the operating system that can conflict with one another or other programs. To turn the extensions back on, restart the computer normally.

Start the program, and perform the same steps that resulted in the original problem.

If the problem continues to occur, the cause is probably not an extension conflict. You must continue troubleshooting the operating system.

For additional information about troubleshooting the operating system, click the following article number to view the article in the Microsoft Knowledge Base:

If the problem no longer occurs with extensions turned off, an extension or control panel is interfering with either the operating system or with Office. You must locate the file that is causing this behavior. To do that, use the process of elimination.

An excellent tool for this process is the Extension Manager control panel, which lists most of the extensions and control panels that are installed in the operating system. To start the process of elimination, follow these steps:

On the Apple menu, click Control Panels, and then click Extension Manager.

In the Extension Manager, make sure that you save the current set of extensions that are running and then switch to the Base Set.

NOTE: The Base Set is located either at the top of the dialog box with a drop-down menu or on the File menu.

Scroll through the list, and turn on all the extensions that start with the word "Microsoft". Restart the computer.

Test the program for the previous behavior.

If the behavior continues, you know that it is with one of the extensions or control panels that is turned on. You must start eliminating files from the list of those currently turned on in the Extension Manager.

If the behavior does not occur with the Base Set + Microsoft extensions turned on, you know that the file that is causing the behavior is not part of that set. You must add extensions to that set (note which extensions or control panels you add), restart the computer, and test for the behavior until it occurs again. After that, you must test the extensions or control panels that were recently added to find one that is causing the behavior.

After you locate the file that is causing the behavior, contact the manufacturer of the software to see whether an updated version is available.

However, if the behavior does not occur when the computer is started with extensions temporarily turned off, but you do not locate the file after you troubleshoot extensions with the Extension Manager, please contact Apple Technical Support for further assistance.

For information about how to contact Apple, click the appropriate article number in the following list to view the article in the Microsoft Knowledge Base:

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.